Wiring worcester 28I to Honeywell cm900 wireless room stat

[D_Hailsham]

The receiver box needs a permanent 230v supply to provide power to run the radio receiver part. Signals received from the transmitter (user control unit) instruct the receiver to open or close a two-way relay which connects A to B (heating) or A to C (cooling).

If the boiler uses 230v on the switched live, then this is provided by linking the L terminal to the A terminal. If the boiler uses a different voltage, e.g 24v ac or dc, then this has to come from the boiler direct to the A terminal and returned to the boiler via the B terminal.

 

[mrgas]

I get it now!! Thanks so much for helping me here guys, I really am greatful!

I guess I should've bought a wireless stat/receiver which was all of 240v then i'd only have needed 3 wires!

Anyway I get it now and will get the wiring done tonight

It's good to know why you are doing what you are doing.....



James,
You have got a stat that works with 230v on both sides!!!
You DO only need 3 cores and a link wire!!
Are you sure youve got it?

 

[jamesevans]

i thought i had

basically the stat requires the link (which is a perm live also to the receiver)??? unlike a normal prog room sat that does not??? is that correct?

 

[steved101]

the wiring is the same as for a prog room stat, BUT the receiver requires a permanent live supply to work - that's the difference

 

[mrgas]

the wiring is the same as for a prog room stat, BUT the receiver requires a permanent live supply to work - that's the difference

The reciever needs both perm live and a neutral!
Otherwise the same as a wired programmable roomstat.

 

[steved101]

the wiring is the same as for a prog room stat, BUT the receiver requires a permanent live supply to work - that's the difference

The reciever needs both perm live and a neutral!
Otherwise the same as a wired programmable roomstat.

yep, some prog room stats also need a perm live and neutral !! and as well as them both having a switched live (LR) the receiver also needs a perm live to feed the switched live (LR)....... !

 

[D_Hailsham]

Maybe this will help

Untitled

• D_Hailsham
• 10 Jun 2009
• 1

 

[dazcrouch]

Hi. I have just joined up in 2018, looking at a post from 2009!! I have the same boiler and a more advanced RF thermostat. Is anyone still listening, as I need to confirm my proposed wiring.

Thank you in advance